1. Field of the Invention
The present invention relates generally to an apparatus for concentrating substances or materials which are floating at or near the surface of a body of water. More specifically, the present invention is directed to a floatable boom for concentrating brine shrimp eggs which are floating at or near the surface of a body of water.
2. Technology Review
For many years, brine shrimp and their eggs have been harvested from salt water bodies and used as a commercial source of fish food. The eggs of this small crustacean are capable of withstanding drying conditions over extended periods of time. In fact, eggs which were harvested and packed several years ago can be hatched, and young brine shrimp raised, when the eggs are returned to salt water. This tremendous capacity of the eggs to withstand drying conditions makes them an ideal source of commercial fish food.
Brine shrimp and their eggs are typically found in colonies which form thin, floating layers on the surface of bodies of water. The eggs are extremely small in size such that several million eggs may be present in a single ounce of water. The brine shrimp and eggs tend to conglomerate, forming a floating layer occupying the top one quarter inch of water. This floating layer is carried by the tide and the wind, eventually being deposited on the shoreline.
Conventional approaches to harvesting brine shrimp eggs often focused on collecting the eggs once they had been deposited on the shoreline. With the use of hand-held nets or shovels, the thin layer of shrimp eggs could be scooped up and placed into storage containers. This approach was far from effective, however, as the harvester was at the whim of the wind and the tide as far as where, and when, the eggs would be deposited along the shoreline.
To deal with these problems of unpredictability, elaborate fencing structures were erected, extending outwardly from the shoreline, to direct incoming shrimp colonies to preselected harvesting sites on the beach. While noticeably more effective in concentrating colonies at predetermined sites, this method was not, however, without its disadvantages. As an initial problem, these extensive fencing structures are understandably expensive. Additionally, this method requires that the harvester have access to large areas of shoreline. Finally, the harvester is still, to a considerable extent, at the whim of the wind and the tide.
Because of the disadvantages inherent in shoreline harvesting methods, an increasing attention has been directed toward methods for harvesting brine shrimp eggs directly from the water. Such methods usually employ a boat or raft equipped with a harvesting device, and some type of boom system to channel the shrimp colonies to the harvesting device.
Various boom systems are disclosed in the prior art as a means for channeling shrimp colonies to the harvesting device. U.S. Pat. No. 3,768,193 by London discloses a wedge shaped collecting structure comprising a water skimming net having a base portion and opposite sidewalls. The net includes a wide, open front portion for skimming and collecting shrimp colonies, and a narrow back portion for funneling the colonies into a harvesting sluice.
U.S. Pat. No. 4,839,062 by Sanders also teaches a wedge shaped collecting structure. In Sanders, the wedge shaped structure is formed by two opposite side arms separated by a cross support. This channeling structure can be selectively raised and lowered by a height adjustment mechanism anchored to a boat.
U.S. Pat. No. 5,042,187 by Bentzley discloses a different method of channeling shrimp colonies to a harvesting device. In Bentzley, a floating boom is positioned to encircle a shrimp colony. A pair of motor driven rollers engage opposite ends of the boom and draw the boom therethrough, decreasing the perimeter of the boom's enclosure. The tightening of the boom's enclosure forces the circumscribed shrimp colony through a harvesting device located at an outlet port to the enclosure.
Certain disadvantages exist, however, with each of the aforementioned channeling systems. In London, a major problem is the short length of the side arms of the channeling structure. Because the entire wedge shaped structure is comprised of a fine net, and this net must be able to hold its configuration as it is skimmed through the water, there is a practical limit on the length of such a structure. The small length of the side arms makes the structure less effective in concentrating large amounts of shrimp eggs at one time. This problem of inefficiency is exacerbated when the device is used in shifting currents or winds.
A channeling device utilizing longer side arms is disclosed in Sanders, wherein a length of approximately 15 feet is contemplated. For practical reasons, however, lengths much greater than this would be prohibited by the height and weight required of the height adjusting mechanism, and, likewise, the size of the boat necessary to support such a mechanism.
In addition to the limitations on the length of the side arms, the Sanders device suffers from other disadvantages. Significantly is the fact that the individual side arms are difficult to adjust in a horizontal, or side-to-side, fashion. While the structure permits adjustment of the vertical height of the side arms so that the side arms may rest at the desired depth in the water, the structure is not easily adjusted in a horizontal fashion. This presents considerable problems to the harvester faced with shifting currents or shifting winds. In order to correct for the changing position of the shrimp colonies, the harvester must steer the entire boat so that the side arms are positioned most favorably.
Bentzley discloses an apparatus which enables the harvester to utilize a boom of a much greater size than what had previously been used, but this method is not without its own set of drawbacks. One major disadvantage of this type of system is that it requires repeated efforts to reposition the boom each time the boom is drawn in by the retrieval system. In order to reposition the boom to encircle another colony of floating shrimp eggs, a considerable amount of manpower and, most likely, at least one additional boat will be required. This results in a process that is both labor intensive as well as time consuming.
It will be appreciated, then, that it would be an advancement in the art if one could provide a boom that is longer than conventional straight booms and capable of being independently directed to a shifting target of floating shrimp eggs. It would be a further improvement if the boom could be directed in a simple, convenient manner that did not require either steering the entire boat in a particular manner or removing the boom from the water and replacing it. It would be a still further improvement if such a boom could be controlled remotely.